DUV 조사법으로 제조된 상부 게이트 자기 정렬 비정질 InGaZnO 박막 트랜지스터의 신뢰성 평가

Abstract

In this study, we fabricated self-aligned coplanar a-IGZO top gate TFT with deep-ultraviolet (DUV) irradiation at source/drain region. The electrical properties of the a-IGZO TFT have a field-effect mobility of 13.2 cm2/V∙s, a threshold voltage of 3.2V, a subthreshold swing value of 0.32V/decade, and an on/off current ratio of 8.8x108,repectively.

We evaluated PBS and PBTS stability behavior of self-aligned coplanar a-IGZO top gate TFT fabricated by DUV irradiation. The values of threshold voltage shift (ΔVTH) under PBS and PBTS are 1.2 V and 1.3 V, respectively. Also, PBTS stabilities were measured with different channel lengths from 10μm to 80 μm. There was no significant difference in ΔVTH (from1.1 V~1.3 V). From these results, n+ doped region formed by DUV irradiation technique did not affect PBTS stability. Also, electrical properties such as field-effect mobility (μFE), subthreshold swing (S/S) and on/off ratio are not nearly change under PBS and PBTS condition for 3600 s. These results indicate that additional no degradation by thermal stress. In addition, channel length modulation (ΔL) and width-normalized contact resistance (RSDW) of a-IGZO TFT with DUV irradiation were extracted as 1.07μm and 87.5 Ω, respectively. Moreover,ΔL and RSDW are maintained even after PBTS condition, which suggests that PBTS condition did not influence on effect of n+ doped region by DUV irradiation.

Consequently, n+ doped region by DUV irradiation was not affected and did not affect instability of self-aligned coplanar TFTs under PBTS condition which give possibility to be applied to high-resolution display and OLED display back-plane.